Measuring Method, Inspection Method, Inspection Device, Semiconductor Device, Method of Manufacturing a Semiconductor Device, and Method of Manufacturing an Element Substrate

ABSTRACT

An inspection method which simplifies an inspection step by eliminating the need to set probes on wiring or probe terminals, and an inspection device for performing the inspection step. A voltage is applied to each of inspected circuits or circuit elements to operate the same. Signal processing is performed on an output from each inspected circuit or circuit element during operation to form a signal (operation information signal) including information on the operating condition of the circuit or the circuit element. The operation information signal is amplified and the amplitude of an alternating current voltage separately input is modulated with the amplified operation information signal. The voltage of the modulated alternating current is read in a non-contact manner to determine whether the corresponding circuit or circuit element is non-defective or defective.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a measuring method in which a circuitor a circuit element of a semiconductor device is operated and an outputfrom the circuit or the circuit element is read, and to a method ofinspecting by using the measuring method to inspect whether a pixelportion operates normally. More particularly, the present inventionrelates to a non-contact type inspection method and a non-contact typeinspection device using the non-contact type inspection method. Thepresent invention also relates to a method of manufacturing asemiconductor device, which includes an inspection step using theinspection method, and to a semiconductor device manufactured by usingthe manufacturing method. Further, the present invention relates to amethod of manufacturing an element substrate including an inspectionstep using the inspection method, and to an element substratemanufactured by using the manufacturing method.

2. Description of the Related Art

In recent years, attention have been paid on techniques for forming athin-film transistor (TFT) by using a semiconductor film (having athickness of about several nanometers to several hundred nanometers)formed on a substrate having an insulating surface. This is because thedemand for active matrix semiconductor display devices included in thecategory of semiconductor devices has been increased. Typical examplesof the active matrix semiconductor display devices include liquidcrystal displays, organic light emitting diode (OLED) displays, anddigital micromirror devices (DMDs).

A high degree of mobility can be achieved in TFTs in which asemiconductor film of a crystalline structure is used as an active layer(crystalline TFTs). Therefore, it is possible to realize an activematrix semiconductor display device capable of high-resolution imagedisplay by forming TFTs of such a kind with functional circuitsintegrated on one substrate.

An active matrix semiconductor display device is completed by performingvarious manufacturing processes. For example, essential processes formanufacturing an active matrix liquid crystal display are a patternforming process for performing forming and pattern forming of asemiconductor film, a color filter forming process for realizing a colordisplay, a cell assembly process for forming a liquid crystal panel byenclosing a liquid crystal between an element substrate having devicesincluding a semiconductor and a counter substrate having a counterelectrode, and a module assembly process for completing the liquidcrystal display by attaching drive components for operating the liquidcrystal panel and a backlight to the liquid crystal panel assembled inthe cell assembly process.

Ordinarily, each of the above-described processes includes an inspectionstep though the requirements for inspection steps therein vary more orless, depending on the kind of the liquid crystal display. If adefective can be picked out in an earlier stage of the manufacturingprocess before it is finished as a product, execution of the subsequentprocesses with respect to the defective panel can be avoided. Thereforethe inspection step is highly effective in reducing the manufacturingcost.

The pattern forming process includes as one of its inspection steps adefect inspection after pattern forming.

The defect inspection after pattern forming is an inspection fordetecting, after pattern forming, a portion where a malfunction occursdue to variation in width of semiconductor film, insulating film andwiring pattern (hereafter, simply referred to as a pattern), or aportion where a wiring is broken or short-circuited by dust or by filmforming failure, or for ascertaining whether circuit or circuit elementto be inspected operates normally.

Methods for such defect inspection are generally grouped into an opticalinspection method and a probe inspection method.

An optical inspection method is a method of identifying a faulty portion(defect) by reading with a CCD or the like a pattern formed on asubstrate and by comparing the read pattern with a reference pattern. Aprobe inspection method is a method of determining whether a portion isdefective or non-defective by setting fine pins (probes) on terminals onthe substrate side and by measuring a current or voltage between theprobes. Generally, the former is called a non-contact type inspectionmethod and the latter is called a contact stylus type inspection method.

Although it is possible to determine whether an element substrate isdefective or non-defective by using either of these inspection methods,each inspection method has both advantages and disadvantages.

The optical inspection method have a problem in that if the inspectionis performed after the completion of formation of a plurality of layeredpatterns, it is difficult to identify each pattern in lower layers, andit is, therefore, difficult to determine whether a circuit or a circuitelement is defective or non-defective by performing detection of adefective portion. To avoid this problem, the inspection may beperformed each time a pattern is formed. In such a case, however, theinspection step is complicated and the time required to perform thewhole manufacturing process is increased. The probe inspection methodshave a problem in that when probes are set directly on wiring or probeterminals, there is a fear of the wiring or probe terminals beingscratched to produce minute dust. Dust produced during the inspectionstep becomes a cause of an undesirable result, i.e., a reduction inyield in subsequent processes.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above-describedproblems, and an object of the present invention is to establish afurther simplified inspection method which does not require settingprobes on wiring or probe terminals, and to provide an inspection deviceusing the inspection method.

The inventors of the present invention have conceived that a current maybe allowed to flow a wiring on an element substrate by causing anelectromotive force to be produced in the wiring by electromagneticinduction without setting probes.

More specifically, a substrate (inspection substrate) for inspection ofthe element substrate is separately provided. The inspection substratehas primary coils for input (referred to as “input primary coil” or“first primary coil” in this specification) and secondary coils foroutput (hereinafter referred to as “output secondary coil” or “secondsecondary coil”). The element substrate to be inspected has secondarycoils for input (hereinafter referred to as “input secondary coil” or“first secondary coil”) and primary coils for output (hereinafterreferred to as “output primary coil” or “second primary coil”).

Each of the input primary coils, the input secondary coils, the outputprimary coils and output secondary coils can be formed by patternforming a conductive film formed on a substrate. In the presentinvention, the coil used as each of the input primary coils, the inputsecondary coils, the output primary coils and output secondary coils isnot a coil having a magnetic material provided at a center to form amagnetic path but a coil having no magnetic material at a center.

The input primary coils provided on the inspection substrate and theinput secondary coils provided on the element substrate are superposedon each other with a certain spacing set therebetween, and analternating current voltage (ac voltage) is applied between a pair ofterminals of each of the input primary coils to generate electromotiveforce between a pair of terminals of the corresponding input secondarycoil.

It is desirable to minimize the spacing between the input primary coilsand the input secondary coils. It is preferred that the input primarycoils and the input secondary coils be set closer to each other as longas the spacing therebetween can be controlled.

In this specification, an application of a voltage to a coil isequivalent to that of the voltage between the pair of terminals of thecoil, and input of a signal to a coil is equivalent to the applicationof the voltage of the signal between the pair of terminals of the coil.

Alternating current voltages generated as the electromotive force acrossthe input secondary coils may be rectified and smoothed appropriately ina circuit on the element substrate to obtain dc voltages used to drivethe circuits or the circuit elements provided on the element substrate(referred to as “power supply voltage”). Also, the waveform ofalternating current voltages generated as the electromotive force acrossthe input secondary coils may be appropriately shaped by a waveformshaping circuit or the like to form signals having voltages used todrive the circuits or the circuit elements provided on the elementsubstrate (referred to as “drive signal”).

The drive signals or power supply voltages thus obtained are supplied tothe circuits or the circuit elements formed on the element substrate.The circuits or the circuit elements operate in certain ways by thedrive signals or power supply voltages. Outputs from some of thecircuits or the circuit elements to be inspected are supplied to aninspection-only circuit the whole of which is provided on the elementsubstrate.

The voltage at any point in each circuit or circuit element may be inputto the inspection-only circuit as an output from the circuit or thecircuit element if it enables ascertainment as to whether the circuit orthe circuit element is operating normally.

The ac voltages generated as the electromotive force across the inputsecondary coils are also input to the inspection-only circuit. Theinspection-only circuit is constituted mainly of means (1) forperforming signal processing on the outputs from the inspected circuitsor circuit elements to obtain signals (operation information signals)including information on the operating conditions of the inspectedcircuits or circuit elements, means (2) for amplifying the operationinformation signals, and means (3) for modulating the amplitudes of theac voltages input to the inspection-only circuit with the amplifiedoperation information signals and for outputting the voltage of themodulated amplitudes. In this specification, a signal having an acvoltage is referred to as “ac signal” and an ac signal in a modulatedstate is referred to as “modulated signal”.

It is not essentially necessary to provide the means (2) for amplifyingthe operation information signals. In this specification, the means (3)for modulating the amplitudes of the ac voltage input to theinspection-only circuit with the amplified operation information signalsand for outputting the modulated amplitudes is referred to as“modulation circuit”.

Each ac modulated signal output from the inspection-only circuit issupplied to one of the pair of terminals of the corresponding one of theoutput primary coils provided on the element substrate. A constantvoltage is applied to the other terminal of the output primary coil. Theoutput primary coils provided on the element substrate and supplied withsuch a signal and voltage and the output secondary coils provided on theinspection substrate are superposed on each other with a certain spacingset therebetween, thereby generating the electromotive force between thepairs of terminals of the output secondary coils.

It is desirable to minimize the spacing between the output primary coilsand the output secondary coils. It is preferred that the output primarycoils and the output secondary coils be set closer to each other as longas the spacing therebetween can be controlled.

A constant voltage is applied to one of the pair of terminals of eachoutput secondary coil. The value of the voltage at the other terminal ofthe output secondary coil is determined by the voltage of the modulatedsignal. Therefore, it is possible to ascertain whether the correspondinginspected circuit or circuit element is operating normally form thevalue of the voltage at the other terminal of the output secondary coil.

If the frequency of the ac voltage input to the inspection-only circuitis increased, the frequency of the modulated signals supplied from theinspection-only circuit to the terminals of the output primary coils isalso increased. The impedance of each coil is determined by variousfactors, e.g., coil design, including the number of turns and the sizeof the coil, and the frequency of the signal input to the coil.Therefore, it is desirable that the frequency of the ac voltages beforemodulation which are input to the inspection-only circuit be determinedby considering the other factors essential in determination of the coilimpedance value.

Each operation information signal may have a dc component in some cases,depending on the operating condition of the corresponding inspectedcircuit or circuit element. Even if the operation information signal hasa dc component, it is possible to produce, between the terminals of theoutput secondary coil, an electromotive force including information on adefective/non-defective condition by supplying the ac modulated signalformed by the modulation with the operation information signal to theterminal of the output primary coil.

It is not always necessary to sort pixels into two groups, i.e.,non-defectives and defectives in terms of operating condition. Thepixels may be sorted into a plurality of ranks according to theoperating condition.

It is not essentially necessary to provide the input primary coils andthe output secondary coils on the same inspection substrate. The inputprimary coils and the output secondary coils may be respectively formedon different substrates.

Weak electromagnetic waves or electric fields generated from thecircuits or the circuit elements when the circuits or the circuitelements are driven may be monitored to detect a portion not operatingnormally from the multiplicity of the circuits or circuit elementswithout using the output primary coils and the output secondary coils.

In such a case, any of various sorts of information on theelectromagnetic waves or electric fields can be monitored and used. Morespecifically, it is possible to collect the frequency, phase, intensity,time, etc., as information on the electromagnetic wave or electric fieldin various dimensions. According to the present invention, any sort ofinformation on the electromagnetic wave or electric field may be used ifit enables a detection of a portion not operating normally in themultiplicity of the circuits or circuit elements.

A well-known method may be used as a method of monitoring the weakelectromagnetic wave or electric field generated at each circuit orcircuit element.

The above-described structures of the present invention enable thedetection of defective portions and a determination of adefective/non-defective condition of each inspected circuit or circuitelement without setting probes directly on wirings or terminals. Thepossibility of minute dust being produced by setting probes iseliminated to prevent a reduction in yield in subsequent processes. Theinspection method of the present invention, unlike optical inspectionmethods, enables a defective/non-defective determination of all thepattern forming steps by one inspection step, thus simplifying theinspection step.

The structures of the present invention will be described in more detailbelow.

The present invention relates to a method of measuring a circuit or acircuit element, the method including the steps of:

operating the circuit or the circuit element by applying a voltage tothe circuit or the circuit element in a non-contact manner; and

reading a voltage output from the circuit or the circuit element in anon-contact manner.

The present invention may have such a feature that the operatingcondition of the circuit or the circuit element is inspected by usingthe voltage output from the circuit or the circuit element which is readby the measuring method.

The present invention also relates to a method of measuring a circuit ora circuit element, the method including the steps of:

operating the circuit or the circuit element by applying a voltage tothe circuit or the circuit element in a non-contact manner;

forming a modulated signal by modulating an ac voltage with a voltageoutput from the circuit or the circuit element; and

reading the voltage of the modulated signal in a non-contact manner.

The present invention may have such a feature that the operatingcondition of the circuit or the circuit element is inspected by usingthe voltage of the modulated signal read by the measuring method.

The present invention also relates to a method of inspecting a circuitor a circuit element, the method including the steps of:

operating the circuit or the circuit element by applying a voltage tothe circuit or the circuit element in a non-contact manner;

reading a voltage output from the circuit or the circuit element in anon-contact manner; and

inspecting the operating condition of the circuit or the circuitelement.

The present invention also relates to a method of inspecting a circuitor a circuit element, the method including the steps of:

operating the circuit or the circuit element by applying a voltage tothe circuit or the circuit element in a non-contact manner;

forming a modulated signal by modulating an ac voltage with a voltageoutput from the circuit or the circuit element;

reading the voltage of the modulated signal in a non-contact manner; and

inspecting the operating condition of the circuit or the circuitelement.

The present invention also relates to a method of inspecting a circuitor a circuit element, the method including the steps of:

applying a first ac voltage between a pair of terminals of a first coil;

overlapping the first coil and a second coil with a certain spacing settherebetween;

forming a signal for operating the circuit or the circuit element from asecond ac voltage generated between a pair of terminals of the secondcoil;

operating the circuit or the circuit element by inputting the signal tothe circuit or the circuit element;

forming a modulated signal by modulating a third ac voltage with avoltage output from the circuit or the circuit element;

applying the voltage of the modulated signal between a pair of terminalsof a third coil;

overlapping the third coil and a fourth coil with a certain spacing settherebetween; and

inspecting the operating condition of the circuit or the circuit elementthrough a fourth ac voltage generated between a pair of terminals of thefourth coil.

The present invention also relates to a method of inspecting a circuitor a circuit element, the method including the steps of:

applying a first ac voltage between a pair of terminals of a first coil;

overlapping the first coil and a second coil with a certain spacing settherebetween;

operating the circuit or the circuit element by rectifying a second acvoltage generated between a pair of terminals of the second coil orshaping the waveform of the voltage to be applied to the circuit or thecircuit element;

forming a modulated signal by modulating a third ac voltage with avoltage output from the circuit or the circuit element;

applying the voltage of the modulated signal between a pair of terminalsof a third coil;

overlapping the third coil and a fourth coil with a certain spacing settherebetween; and

inspecting the operating condition of the circuit or the circuit elementthrough a fourth ac voltage generated between a pair of terminals of thefourth coil.

The present invention may have such a feature that the frequency of thethird ac voltage is higher than the frequency of the first ac voltage.

The present invention also relates to a method of inspecting a circuitor a circuit element, the method including the steps of:

generating ac voltages differing in phase between pairs of terminals ofa plurality of second coils by applying first ac voltages differing inphase between pairs of terminals of a plurality of first coils and byoverlapping the plurality of first coils and the plurality of secondcoils with a certain spacing set therebetween;

generating a dc voltage by rectifying the ac voltages generated betweenthe pairs of terminals of the plurality of second coils, which differfrom each other in phase and by adding together the rectified acvoltages;

generating an ac voltage between a pair of terminals of a fourth coil byapplying a second ac voltage between a pair of terminals of a third coiland by overlapping the third coil and the fourth coil with a certainspacing set therebetween;

modulating the ac voltage generated between the pair of terminals of thefourth coil with a voltage output from the circuit or the circuitelement, by applying the dc voltage to the circuit or the circuitelement;

generating an ac voltage between a pair of terminals of a sixth coil byapplying the modulated ac voltage between a pair of terminals of a fifthcoil and by overlapping the fifth coil and the sixth coil with a certainspacing set therebetween; and

inspecting the operating condition of the circuit or the circuit elementthrough the ac voltage generated across the sixth coil.

The present invention may have such a feature that the plurality offirst coils, the third coil and the sixth coil are formed on a firstinsulating surface, and the circuit or the circuit element, theplurality of second coils, the fourth coil and the fifth coil are formedon a second insulating surface.

The present invention may have such a feature that the frequency of thesecond ac voltage is higher than the frequency of the first ac voltage.

The present invention may have such a feature that the plurality offirst coils, the plurality of second coils, the third coil, the fourthcoil, the fifth coil and the sixth coil have their wirings formed alongone plane, the wirings having a spiral shape.

The present invention also relates to a method of inspecting a circuitor a circuit element, the method including the steps of:

generating ac voltages differing in phase between pairs of terminals ofa plurality of second coils by applying first ac voltages differing inphase between pairs of terminals of a plurality of first coils and byoverlapping the plurality of first coils and the plurality of secondcoils with a certain spacing set therebetween;

generating a dc voltage by rectifying the ac voltages generated betweenthe pairs of terminals of the plurality of second coils, which differfrom each other in phase and by adding together the rectified acvoltages;

generating an ac voltage between a pair of terminals of a fourth coil byapplying a second ac voltage between a pair of terminals of a third coiland by overlapping the third coil and the fourth coil with a certainspacing set therebetween;

generating a voltage for driving the circuit or the circuit element byshaping the waveform of the ac voltage generated between the pair ofterminals of the fourth coil;

generating an ac voltage between a pair of terminals of a sixth coil byapplying a third ac voltage between a pair of terminals of a fifth coiland by overlapping the fifth coil and the sixth coil with a certainspacing set therebetween;

modulating the ac voltage generated between the pair of terminals of thesixth coil with a voltage output from the circuit or the circuitelement, by applying the dc voltage and the voltage for driving thecircuit or the circuit element to the circuit or the circuit element;

generating an ac voltage between a pair of terminals of an eighth coilby applying the modulated ac voltage between a pair of terminals of aseventh coil and by overlapping the seventh coil and the eighth coilwith a certain spacing set therebetween; and

inspecting the operating condition of the circuit or the circuit elementthrough the ac voltage generated across the eighth coil.

The present invention may have such a feature that the plurality offirst coils, the third coil, the fifth coil and the eighth coil areformed on a first insulating surface, and the circuit or the circuitelement, the plurality of second coils, the fourth coil, the sixth coiland the seventh coil are formed on a second insulating surface.

The present invention may have such a feature that the frequency of thethird ac voltage is higher than the frequency of the first ac voltage orthe second ac voltage.

The present invention may have such a feature that the plurality offirst coils, the plurality of second coils, the third coil, the fourthcoil, the fifth coil, the sixth coil, the seventh coil and the eighthcoil have their wirings formed along one plane, the wirings having aspiral shape.

The present invention also relates to a method of inspecting a circuitor a circuit element, the method including the steps of:

generating an ac voltage between a pair of terminals of a second coil byapplying a first ac voltage between a pair of terminals of a first coiland by overlapping the first coil and the second coil with a certainspacing set therebetween;

generating a voltage for driving the circuit or the circuit element byshaping the waveform of the ac voltage generated between the pair ofterminals of the second coil;

generating an ac voltage between a pair of terminals of a fourth coil byapplying a second ac voltage between a pair of terminals of a third coiland by overlapping the third coil and the fourth coil with a certainspacing set therebetween;

modulating the ac voltage generated between the pair of terminals of thefourth coil with a voltage output from the circuit or the circuitelement, by applying the voltage for driving the circuit or the circuitelement to the circuit or the circuit element;

generating an ac voltage between a pair of terminals of a sixth coil byapplying the modulated ac voltage between a pair of terminals of a fifthcoil and by overlapping the fifth coil and the sixth coil with a certainspacing set therebetween; and

inspecting the operating condition of the circuit or the circuit elementthrough the ac voltage generated across the sixth coil.

The present invention may have such a feature that the first coil, thethird coil and the sixth coil are formed on a first insulating surface,and the circuit or the circuit element, the second coil, the fourth coiland the fifth coil are formed on a second insulating surface.

The present invention may have such a feature that the frequency of thesecond ac voltage is higher than the frequency of the first ac voltage.

The present invention may have such a feature that the first coil, thesecond coil, the third coil, the fourth coil, the fifth coil and thesixth coil have their wirings formed along one plane, the wirings havinga spiral shape.

The present invention may have such a feature that the distance betweenthe first insulating surface and the second insulating surface iscontrolled by causing a fluid to flow between the first insulatingsurface and the second insulating surface.

The present invention also relates to a device for inspecting a circuitor a circuit element provided on an element substrate, the devicehaving:

a first primary coil;

a second secondary coil;

means for overlapping the first primary coil and a first secondary coilprovided on the element substrate, with a certain spacing set betweenthe first primary coil and the first secondary coil;

means for overlapping the second secondary coil and a second primarycoil provided on the element substrate, with a certain spacing setbetween the second secondary coil and the second primary coil;

means for applying an ac voltage between a pair of terminals of thefirst primary coil; and

means for inspecting the operating condition of the circuit or thecircuit element through an ac voltage generated between a pair ofterminals of the second secondary coil.

The present invention also relates to a device for inspecting a circuitor a circuit element provided on an element substrate, the devicehaving:

a first primary coil;

a second secondary coil;

means for overlapping the first primary coil and a first secondary coilprovided on the element substrate, with a certain spacing set betweenthe first primary coil and the first secondary coil;

means for overlapping the second secondary coil and a second primarycoil provided on the element substrate, with a certain spacing setbetween the second secondary coil and the second primary coil;

means for applying an ac voltage between a pair of terminals of thefirst primary coil;

means for amplifying or buffer-amplifying an ac voltage generatedbetween a pair of terminals of the second secondary coil; and

means for inspecting the operating condition of the circuit or thecircuit element through the ac voltage amplified or buffered andamplified.

The present invention also relates to a device for inspecting a circuitor a circuit element provided on an element substrate, the devicehaving:

a first primary coil;

a second secondary coil;

means for overlapping the first primary coil and a first secondary coilprovided on the element substrate, with a certain spacing set betweenthe first primary coil and the first secondary coil;

means for overlapping the second secondary coil and a second primarycoil provided on the element substrate, with a certain spacing setbetween the second secondary coil and the second primary coil;

means for applying an ac voltage between a pair of terminals of thefirst primary coil; and

means for inspecting the operating condition of the circuit or thecircuit element through an ac voltage generated between a pair ofterminals of the second secondary coil,

wherein the ac voltage generated between the pair of terminals of thesecond secondary coil includes information on the operating condition ofthe circuit or the circuit element or the location of a defectiveportion.

The present invention further relates to a device for inspecting acircuit or a circuit element provided on an element substrate, thedevice having:

a first primary coil;

a second secondary coil;

means for overlapping the first primary coil and a first secondary coilprovided on the element substrate, with a certain spacing set betweenthe first primary coil and the first secondary coil;

means for overlapping the second secondary coil and a second primarycoil provided on the element substrate, with a certain spacing setbetween the second secondary coil and the second primary coil;

means for applying an ac voltage between a pair of terminals of thefirst primary coil;

means for amplifying or buffer-amplifying an ac voltage generatedbetween a pair of terminals of the second secondary coil; and

means for inspecting the operating condition of the circuit or thecircuit element through the ac voltage amplified or buffered andamplified,

wherein the ac voltage amplified or buffered and amplified includesinformation on the operating condition of the circuit or the circuitelement or the location of a defective portion.

The present invention may have such a feature that the distance betweenthe first primary coil and the first secondary coil is controlled bycausing a fluid to flow between the first primary coil and the firstsecondary coil.

The present invention may have such a feature that the distance betweenthe second primary coil and the second secondary coil is controlled bycausing a fluid to flow between the second primary coil and the secondsecondary coil.

The present invention may have such a feature that the first primarycoil has its wiring formed along one plane, the wiring having a spiralshape.

The present invention may have such a feature that the second secondarycoil may have its wiring formed along one plane, the wiring having aspiral shape.

The present invention also relates to a method of manufacturing asemiconductor device, the method including the steps of:

manufacturing a circuit or a circuit element;

operating the circuit or the circuit element after manufacture byapplying a voltage to the circuit or the circuit element in anon-contact manner;

reading a voltage output from the circuit or the circuit element in anon-contact manner; and

inspecting the operating condition of the circuit or the circuitelement.

The present invention also relates to a method of manufacturing asemiconductor device, the method including the steps of:

manufacturing a circuit or a circuit element;

operating the circuit or the circuit element after manufacture byapplying a voltage to the circuit or the circuit element in anon-contact manner;

forming a modulated signal by modulating an ac voltage with a voltageoutput from the circuit or the circuit element;

reading the voltage of the modulated signal in a non-contact manner; and

inspecting the operating condition of the circuit or the circuitelement.

The present invention also relates a method of manufacturing asemiconductor device, the method including the steps of:

manufacturing a circuit or a circuit element, a first coil, a secondcoil, a third coil, and a fourth coil;

applying a first ac voltage between a pair of terminals of the firstcoil after manufacture;

overlapping the first coil and the second coil with a certain spacingset therebetween;

forming a signal for operating the circuit or the circuit element from asecond ac voltage generated between a pair of terminals of the secondcoil;

operating the circuit or the circuit element by inputting the signal tothe circuit or the circuit element;

forming a modulated signal by modulating a third ac voltage with avoltage output from the circuit or the circuit element;

applying the voltage of the modulated signal between a pair of terminalsof the third coil;

overlapping the third coil and the fourth coil with a certain spacingset therebetween; and

inspecting the operating condition of the circuit or the circuit elementthrough a fourth ac voltage generated between a pair of terminals of thefourth coil.

The present invention also relates to a semiconductor device having acircuit or a circuit element, means for applying a voltage to thecircuit or the circuit element in a non-contact manner, means forforming a modulated signal by modulating an ac voltage with a voltageoutput from the circuit or the circuit element, and means for outputtingthe voltage of the modulated signal in a non-contact manner.

The present invention also relates to a semiconductor device having:

a circuit or a circuit element;

means for applying a voltage to the circuit or the circuit element in anon-contact manner by using a first coil;

means for forming a modulated signal by modulating an ac voltage with avoltage output from the circuit or the circuit, element; and means foroutputting the voltage of the modulated signal in a non-contact mannerby using a second coil.

The present invention also relates to a semiconductor device having:

a circuit or a circuit element;

a first coil;

a second coil;

a third coil;

means for rectifying a first ac voltage generated between a pair ofterminals of the first coil or shaping the waveform of the voltage, forthe application to the circuit or the circuit element; and

means for forming a modulated signal by modulating a second ac voltagegenerated between a pair of terminals of the second coil with a voltageoutput from the circuit or the circuit element, and for applying themodulated signal between a pair of terminals of the third coil.

The present invention also relates to a semiconductor device having:

a circuit or a circuit element;

a plurality of first coils;

a second coil;

a third coil;

means for generating a dc voltage by rectifying first ac voltagesgenerated between pairs of terminals of the plurality of first coils andby adding together the rectified voltages, and for applying thegenerated dc voltage to the circuit or the circuit element; and

means for forming a modulated signal by modulating a second ac voltagegenerated between a pair of terminals of the second coil with a voltageoutput from the circuit or the circuit element, and for applying themodulated signal between a pair of terminals of the third coil.

The present invention also relates to a semiconductor device having:

a circuit or a circuit element;

a first coil;

a plurality of second coils;

a third coil;

a fourth coil;

means for rectifying a first ac voltage generated between a pair ofterminals of the first coil or shaping the waveform of the voltage, forthe application to the circuit or the circuit element;

means for generating a dc voltage by rectifying second ac voltagesgenerated between pairs of terminals of the plurality of second coilsand by adding together the rectified voltages, and for applying thegenerated dc voltage to the circuit or the circuit element; and

means for forming a modulated signal by modulating a third ac voltagegenerated between a pair of terminals of the third coil with a voltageoutput from the circuit or the circuit element, and for applying themodulated signal between a pair of terminals of the fourth coil.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A and 1B are top views of an inspection substrate and an elementsubstrate;

FIG. 2 is a block diagram of the inspection substrate and the elementsubstrate;

FIGS. 3A and 3B are enlarged views of coils;

FIGS. 4A and 4B are perspective views of the inspection substrate andthe element substrate at the time of inspection;

FIG. 5 is a circuit diagram of a waveform shaping circuit;

FIG. 6 is a circuit diagram of a rectifier circuit;

FIGS. 7A and 7B are diagrams showing changes with time in a signalobtained as a pulsating current by rectification of an ac current;

FIGS. 8A, 8B, and 8C are diagrams showing changes with time in a dcsignal obtained by the addition of pulsating currents;

FIG. 9 is a circuit diagram of an inspection-only circuit;

FIG. 10 is a circuit diagram of an inspection-only circuit having outputpads;

FIG. 11 is a block diagram of an element substrate of a liquid crystaldisplay;

FIG. 12 is a block diagram of an element substrate of an OLED display;

FIG. 13 is a top view of a large-size element substrate;

FIG. 14 is a top view of a large-size element substrate;

FIG. 15 is a flowchart showing a procedure of inspection steps inaccordance with the present invention;

FIGS. 16A to 16D are top and cross-sectional views of coils;

FIG. 17 is a block diagram of an inspection device; and

FIGS. 18A and 18B are circuit diagrams of rectifier circuits.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1A is a top view of an inspection substrate used to performinspection in accordance with the present invention, and FIG. 1B is atop view of an element substrate to be inspected. In an embodiment ofthe present invention, an inspection method will be described withrespect to inspection of an element substrate of a liquid crystaldisplay as an example. However, use of the inspection method of thepresent invention is not limited to inspection of a liquid crystaldisplay. The inspection method of the present invention can be used toinspect any semiconductor device formed by using a semiconductor.

The inspection substrate shown in FIG. 1A has a substrate 100 on whichare formed an input primary coil formation portion 101, an outputsecondary coil formation portion 102, an external input buffer 103, anexternal output buffer 104, and a connector connection portion 105. Theinspection substrate of this specification includes the substrate 100and all circuits or circuit elements formed on the substrate 100.

The number of input primary coil formation portions 101, the number ofoutput secondary coil formation portions 102, and the layout of inputprimary coil formation portions 101 and output secondary coil formationportions 102 provided on the inspection substrate are not limited tothose in FIG. 1A. The number of input primary coil formation portions101, the number of output secondary coil formation portions 102, and thelayout of input primary coil formation portions 101 and output secondarycoil formation portions 102 can be freely set by a designer.

The element substrate shown in FIG. 1B has a substrate 110 on which areprovided a signal line drive circuit 111, a scanning line drive circuit112, a pixel portion 113, routing wiring 114, a connector connectionportion 115, a waveform shaping or rectifier circuit 116, an inputsecondary coil formation portion 117, an output primary coil formationportion 118, an inspection-only circuit 119, and coil wiring 120. Theelement subs hate of this specification includes the substrate 110 andall circuits or circuit elements formed on the substrate 110. Therouting wiring 114 is wiring for supplying drive signals and powersupply voltages to the pixel portion and the drive circuits provided onthe element substrate.

The number of input secondary coil formation portions 117, the number ofoutput primary coil formation portions 118, and the layout of inputsecondary coil formation portions 117 and output primary coil formationportions 118 provided on the element substrate are not limited to thosein FIG. 1B. The number of input secondary coil formation portions 117,the number of output primary coil formation portions 118, and the layoutof input secondary coil formation portions 117 and output primary coilformation portions 118 can be freely set by the designer.

A flexible printed circuit (FPC), tape automated bonding (TAB)conductors, or the like are connected to the connector connectionportion 115 in a process following the inspection step. Afterinspection, the element substrate is cut along a line represented by adotted line A-A′ so that the coil wiring 120 is cut off physically andelectrically.

The operation of the element substrate and the inspection substrate inan inspection step will next be described. For ease of understanding ofthe flows of signals in the inspection step, the structures of thecircuits of the element substrate and the inspection substrate shown inFIG. 1 are shown in the block diagram of FIG. 2. The operation will bedescribed with reference to FIGS. 1 and 2.

On the inspection substrate 204, an alternating current signal used forthe inspection is input to the external input buffer 103 from a signalsource 201 or an alternating current power supply 202 via a connectorconnected to the connector connection portion 105. The inspection acsignal is buffered and amplified by the external input buffer 103 isthereafter input to the input primary coil formation portion 101.

In FIGS. 1 and 2, the input ac signal is input to the input primary coilformation portion 101 after being buffered and amplified by the externalinput buffer 103. The present invention, however, is not limited to thisarrangement. An ac signal may be input directly to the input primarycoil formation portion 101 without providing the external input buffer103.

A plurality of input primary coils are formed in the input primary coilformation portion 101. The ac signal is applied between a pair ofterminals of each input primary coil.

On the other hand, a plurality of input secondary coils corresponding tothe plurality of input primary coils of the input primary coil formationportion 101 are formed in the input secondary coil formation portion 117of the element substrate 205. When the ac signal is applied to the inputprimary coils, an ac voltage is generated as electromotive force betweenthe a pair of terminals of each of the input secondary coils byelectromagnetic induction.

The ac voltage generated in each input secondary coil is supplied to thewaveform shaping circuit 116 a or the rectifier circuit 116 b. Thewaveform shaping circuit 116 a or the rectifier circuit 116 b shapes orrectifies the ac voltage waveform to produce drive signals or powersupply voltages.

The produced drive signals or power supply voltages are input to therouting wiring 114 through the coil wiring 120. The input drive signals,the power supply voltages, or the like are supplied to the signal linedrive circuit 111, the scanning line drive circuit 112, and the pixelportion 113.

The pixel portion 113 has a plurality of pixels. A pixel electrode isformed in each pixel. The number of signal line drive circuits and thenumber of scanning line drive circuits are not limited to those shown inFIG. 1A and FIG. 2.

An output from each of the circuits or each of the circuit elementsincluded in the signal line drive circuit 111, the scanning line drivecircuit 112, and the pixel portion 113 is input to the inspection-onlycircuit 119.

For example, the voltage of each terminal of a transistor or the voltageof each pixel electrode in the pixel portion 113 may be input as anoutput from a circuit or a circuit element to the inspection-onlycircuit 119. However, it is not essentially necessary to input theoutputs from the circuits or circuit elements in all the pixels to theinspection-only circuit 119. Only the outputs from the circuits orcircuit elements in some of the pixels selected as desired may be inputto the inspection-only circuit 119. Also, pixels only for inspection(dummy pixels), that are not actually used for display, may be providedin the pixel portion 113 and the output from the circuit or the circuitelement in each of the pixels only for inspection is input to theinspection-only circuit 119. The above is not limited to the pixelportion 113. That is, it is not essentially necessary to input theoutputs from all the circuits or the circuit elements on the elementsubstrate to the inspection-only circuit 119, and only the outputs fromsome of the circuits or the circuit elements on the element substrateselected as desired may be input to the inspection-only circuit 119.Further, circuits or circuit elements only for inspection, that are notactually used for driving, may be formed and the output from each of thecircuits or circuit elements only for inspection may be input to theinspection-only circuit 119.

The inspection-only circuit 119 performs signal processing for the inputsignal, i.e., the output from each of the input circuits or circuitelement, to produce a signal (operation information signal) includinginformation on the operating condition of the inspected circuit orcircuit element. The inspection-only circuit 119 amplifies the operationinformation signal and inputs the amplified signal to a modulationcircuit 121. It is not always necessary to amplify the operationinformation signal. If the operation information signal is notamplified, it is input directly to the modulation circuit 121.

On the other hand, the ac voltage generated in each input secondary coilis input to the inspection-only circuit 119. This signal of the acvoltage is input to the modulation circuit 121 provided in theinspection-only circuit 119.

Then the inspection-only circuit 119 modulates the amplitude of theinput ac voltage in the modulation circuit 121 in accordance with theinput operation information signal and inputs the modulated signal tothe output primary coil formation portion 118.

More specifically, the voltage of the modulated signal input to theoutput primary coil formation portion 118 is input to one of theterminals of the plurality of output primary coils included in theoutput primary coil formation portion 118. A constant voltage is appliedto the other terminal of the output primary coil.

On the other hand, a plurality of output secondary coils correspondingto the plurality of output primary coils of the output primary coilformation portion 118 are formed in the output secondary coil formationportion 102 of the inspection substrate 204. When the ac voltage isapplied between the a pair of terminals of the output primary coil, anac voltage is generated as electromotive force between a pair ofterminals of each output secondary coils by electromagnetic induction.The ac voltage generated between the a pair of terminals of the outputsecondary coils includes information on the operating condition of thecircuit or the circuit element.

A constant voltage is applied to one of a pair of terminals of theoutput secondary coil. The voltage in the other terminal of the outputsecondary coil is amplified by the external output buffer 104 and theninput to an inspection section 203.

It is not essentially necessary to provide the external output buffer104. The voltage in the other terminal of the output secondary coil maybe input directly to the inspection section 203 without being amplified.

The inspection section 203 is capable of determining whether eachcircuit or circuit element is defective or non-defective from the acvoltage including information on the operation condition of the circuitor the circuit element and is capable of locating a defective portion.

Note that, if the frequency of the ac voltage input to theinspection-only circuit is increased, the frequency of the modulatedsignal supplied from the inspection-only circuit to the terminal of theoutput primary coil is also increased. The impedance of the coil isdetermined by various factors, e.g., coil design factors, including thenumber of turns and the size of the coil, and the frequency of thesignal input to the coil. Therefore it is desirable that the value ofthe frequency of the ac voltage before modulation input to theinspection-only circuit be determined by considering the other factorsthat influence the determination of the coil impedance value.

The operation information signal may have a dc component, depending onthe operating condition of the inspected circuit or circuit element.Even if the operation information signal has a dc component, it ispossible to produce, between the terminals of the output secondary coil,electromotive force including information on a defective/non-defectivecondition by supplying the ac modulated signal formed by modulation withthe operation information signal to the terminal of the output primarycoil.

It is not essentially necessary to provide the input primary coils andthe output secondary coils on the same inspection substrate. The inputprimary coils and the output secondary coils may be respectively formedon different substrates.

In FIGS. 1A, 1B, and 2, the input primary coil formation portion where aplurality of input primary coils are formed and the output secondarycoil formation portion where a plurality of output secondary coils areformed are defined separately from each other. The inspection substrateof the present invention, however, is not limited to this arrangement. Aplurality of input primary coils and a plurality of output secondarycoils may be mixedly placed. In such a case, it is not necessary toseparately define a region where the plurality of input primary coilsare formed and a region where the plurality of output secondary coilsare formed.

When the drive signals, the power supply voltages, or the like are inputto the signal line drive circuit 111, the scanning line drive circuit112, and the pixel portion 113, electromagnetic waves or electric fieldsare generated at the circuits or circuit elements in the signal linedrive circuit 111, the scanning line drive circuit 112, and the pixelportion 113. Weak electromagnetic waves or electric fields generatedfrom the circuits or circuit elements when the circuits or circuitelements are driven may be monitored to detect a portion not operatingnormally from the multiplicity of circuits or circuits or circuitelements without using the output primary coils and the output secondarycoils provided as described above.

The intensity of the electric field or electromagnetic wave generated atone of the circuits or circuit elements not operating normally differsfrom that of the electric fields or electromagnetic waves generated atthe circuits or circuit elements operating normally. Therefore theinspection section 203 may monitor the intensities of electromagneticwaves or electric fields generated at the circuits or circuit elementsto determine whether each circuit or circuit element is operatingnormally or to locate a defective portion.

In a case where the output primary coils and the output secondary coilsare not provided, the outputs from the inspection-only circuit 119 areinput to predetermined terminals (pads) in FIG. 2, the intensities ofelectric fields or electromagnetic waves at the pads are measured andthe measured values are input to the inspection section 203, therebyenabling the inspection section 203 to determine whether each inspectedportion is defective or non-defective or to locate a defective portion.

Any method of monitoring electromagnetic waves or electric fields may beused if it ensures sensitivity high enough to enable determination as towhether each circuit or circuit element is operating normally.

The structure of the input primary coils, input secondary coils, outputprimary coils, and output secondary coils (hereinafter referred to as“coils” collectively) will be described in detail.

FIGS. 3A and 3B are enlarged views of coils. The coil shown in FIG. 3Ais formed by spirally winding a conductor and has two ends formed ascoil terminals 301 and 302. The coil shown in FIG. 3B is formed bywinding a conductor so as to have a rectangular shape, and has two endsformed as coil terminals 303 and 304.

A coil entirely formed along one plane by being wound about a point maysuffice as the coil used in the present invention. Therefore theconductor of the coil may be in either of a curved form or an angularform as viewed in a direction perpendicular to the plane along which thecoil is formed.

The number of turns of the coils, the width of the conductor of thecoils and the area occupied by the coils on the substrate may be set asappropriate by the designer.

FIG. 4A shows a state in which the element substrate and the inspectionsubstrate are placed so as to have their portions superposed on eachother. In the example of structure of the coils illustrated in FIG. 4A,the element substrate shown in FIG. 1B and FIG. 2 has input secondarycoils and output primary coils each formed as shown in FIG. 3A, and theinspection substrate shown in FIG. 1A and FIG. 2 has input primary coilsand output secondary coils each formed as shown in FIG. 3A. A connector206 is provided which connects the inspection substrate 204, the signalsource, the ac power supply and the inspection section.

As shown in FIG. 4A, the input primary coil formation portion 101 of theinspection substrate 204 and the input secondary coil formation portion117 of the element substrate 205 are superposed in a state of beingspaced a certain distance apart from each other. It is desirable tominimize this distance. It is preferred that the input primary coilformation portion 101 and the input secondary coil formation portion 117of the element substrate 205 be set closer to each other as long as thedistance therebetween can be controlled.

Also, the output secondary coil formation portion 102 of the inspectionsubstrate 204 and the output primary coil formation portion 118 of theelement substrate 205 are superposed in a state of being spaced acertain distance apart from each other. It is desirable to minimize thisdistance. It is preferred that the output secondary coil formationportion 102 and the output primary coil formation portion 118 be setcloser to each other as long as the distance therebetween can becontrolled.

The distance between the inspection substrate 204 and the elementsubstrate 205 may be maintained by fixing the two substrates. Also, thedistance between the inspection substrate 204 and the element substrate205 may be maintained in such a manner that one of the inspectionsubstrate 204 and the element substrate 205 is fixed and a fluid iscaused to flow through the gap between the inspection substrate 204 andthe element substrate 205 at a certain flow rate or is kept at a certainpressure in the gap between the inspection substrate 204 and the elementsubstrate 205. The fluid used for this purpose is typically a gas or aliquid. A viscous fluid such as a gel may also be used.

FIG. 4B is an enlarged diagram of superposed portions of the inputprimary coil formation portion 101 and the input secondary coilformation portion 117. Input primary coils are indicated by 208 andinput secondary coils are indicated by 207.

The input primary coils 208 and the input secondary coils 207 are woundin the same direction. However, the present invention is not limited tothis arrangement. The primary and secondary coils may be wound inopposite directions.

The distance (L_(gap)) between the primary and secondary coils is set asappropriate by the designer.

The output primary coils in the output primary coil formation portion118 and the output secondary coils in the output secondary coilformation portion 102 are superposed on each other to beelectromagnetically coupled, as are the input primary coils 208 and theinput secondary coils 207 shown in FIG. 4B.

The structure of the waveform shaping circuit 116 a shown in FIG. 2 willbe described in detail.

FIG. 5 shows a connecting state between the signal source 201, the inputprimary coil formation portion 101, the input secondary coil formationportion 117, and the waveform shaping circuit 116 a shown in FIGS. 1A,1B, and 2. A plurality of input primary coils 208 are provided in theinput primary coil formation portion 101. A plurality of input secondarycoils 207 are provided in the input secondary coil formation portion117.

The inspection ac signal supplied from the signal source 201 is input toeach input primary coil 208. More specifically, the voltage of theinspection ac signal from the signal source 201 is applied between the apair of terminals of each input primary coil 208. When the ac signal isinput to the input primary coil 208, an ac voltage is generated aselectromotive force across the corresponding input secondary coil 207and is applied to the waveform shaping circuit 116 a.

The waveform shaping circuit 116 a is an electronic circuit used to formor shape a waveform of a quantity which changes with time, e.g., avoltage or a current. Referring to FIG. 5, the waveform shaping circuit116 a has resistors 501 and 502 and capacitors 503. These circuitelements are combined to form the integrating-type waveform shapingcircuit 116 a. Needless to say, the waveform shaping circuit is notlimited to the structure shown in FIG. 5. To perform waveform shaping,the waveform shaping circuit may use a wave-detection circuit usingdiodes, such as that used in the power supply circuit.

The waveform shaping circuit 116 a used in the present inventiongenerates, specifically, a clock signal (CLK), a start pulse signal(SP), and a video signal from the input ac electromotive force, andoutputs these signals.

The waveform shaping circuit 116 a can generate signals having any otherwaveforms as well as those mentioned above. Signals enablingconfirmation of the operating condition of the circuits or the circuitelements may suffice as signals formed by the waveform shaping circuit116 a.

The signals output from the waveform shaping circuit 116 a are input tocircuits in subsequent stages (signal line drive circuit 111, scanningline drive circuit 112, and pixel portion 113 in FIGS. 1 and 2).

The structure of the rectifier circuit 116 b shown in FIG. 2 will bedescribed in detail.

FIG. 6 shows connections between the ac power supply 202, the inputprimary coil formation portion 101, the input secondary coil formationportion 117, and the rectifier circuit 116 b shown in FIGS. 1A, 1B, and2. A plurality of input primary coils 208 are provided in the inputprimary coil formation portion 101. A plurality of input secondary coils207 are provided in the input secondary coil formation portion 117.

The inspection ac signal supplied from the ac power supply 202 is inputto each input primary coil 208. When the ac signal is input to the inputprimary coil 208, an ac voltage is generated as electromotive forceacross the corresponding input secondary coil 207 and is applied to therectifier circuit 116 b.

“Rectifier circuit” in this embodiment denotes a circuit which generatesa power supply voltage from an ac voltage supplied to it, and “dc powersupply voltage” denotes a voltage applied to each circuit or circuitelement and maintained at a certain level.

The rectifier circuit 116 b shown in FIG. 6 has diodes 601, capacitors604, and resistors 603. Each diode 601 converts the input ac voltageinto a dc voltage by rectification.

FIG. 7A shows changes in alternating current with time beforerectification by the diode 601, and FIG. 7B shows changes in voltagewith time after rectification. As can be understood from comparisonbetween the graph of FIG. 7A and the graph of FIG. 7B, a pulsatingcurrent appears after rectification, whose voltage has a value of zeroor a value with one polarity in every half period.

It is difficult to use the voltage of the pulsating current shown inFIG. 7B as a power supply voltage. Ordinarily, smoothing of such apulsating current is performed by storing, in a capacitor, electriccharge carried by the pulsating current to convert the pulsating currentinto a dc voltage. However, if a capacitor having a capacity largeenough to sufficiently smooth the pulsating current is formed by using athin-film semiconductor, it is necessary to increase the area occupiedby the capacitor to an extremely large value. Therefore smoothing usingsuch a capacitor is not practically realizable. According to the presentinvention, the voltages of pulsating currents having different phasesafter rectification are combined (added) to obtain a smoothed voltage.The above-described arrangement enables pulsating currents to besufficiently smoothed even if the capacitance of smoothing capacitors issmall. Further, a sufficiently high smoothing effect can be achievedwithout positively providing capacitors.

Referring to FIG. 6, ac signals having different phases are input tofour primary coils to output four pulsating current voltages differingin phase through four diodes 601. The four pulsating current voltagesare added together to generate a dc power supply voltage, the level ofwhich is maintained generally constantly. This dc power supply voltageis supplied to one of the circuits in the subsequent stages.

However, the present invention is not limited to the structure shown inFIG. 6, in which four pulsating current signals which are output fromthe four diodes 601, and which differ in phase from each other, areadded together to generate a dc power supply voltage. The number ofphase divisions is not limited to four. The number of phase divisionsmay be freely selected if the voltage obtained by smoothing the outputfrom the rectifier circuit can be used as a power supply voltage.

FIGS. 8A, 8B, and 8C are diagrams each showing changes with time in apower supply voltage obtained by adding a plurality of rectified signalstogether. FIG. 8A shows an example of generation of one power supplyvoltage by the addition of the voltages of four pulsating currentsdiffering in phase.

The voltage generated in the rectifier circuit in accordance with thepresent invention has a ripple which is a component other than thedirect current since it is generated by adding a plurality of pulsatingcurrents. The ripple corresponds to the difference between the maximumand the minimum of the voltage. If the ripple is smaller, the voltagegenerated in the rectifier circuit becomes more approximate to a directcurrent voltage and becomes easier to use as a power supply voltage.

FIG. 8B shows changes with time in a power supply voltage obtained byadding the voltages of eight pulsating currents differing in phase. Fromcomparison with the changes in power supply voltage with time shown inFIG. 8A, it can be understood that the ripple in this case is smaller.

FIG. 8C shows changes with time in a power supply voltage obtained byadding the voltages of sixteen pulsating currents differing in phase.From comparison with the changes in voltage with time shown in FIG. 8B,it can be understood that the ripple in this case is further reduced.

As can be understood from these graphs, the ripple in the power supplyvoltage can be reduced by adding an increased number of pulsatingcurrents differing in phase to approximate the power supply voltage to adc current. Thus, if the number of phase divisions is increased, theeffect of smoothing the power supply voltage output from the rectifiercircuit is improved. Also, if the capacitance of a capacitor 602 isincreased, the effect of smoothing the power supply voltage output fromthe rectifier circuit is improved.

Power supply voltages generated in a rectifier circuit 116 b are outputthrough terminals 610 and 611. More specifically, a voltage closer theground potential is output through the terminal 610, while a powersupply voltage of the positive polarity is output through the terminal611. It is possible to reverse the polarities of the power supplyvoltages by reversely connecting the anode and cathode of the diodes.The diodes 602 connected to the terminals 610 and 611 have the anode andcathode connected reversely relative to those of the diodes 601connected to terminals 612 and 613. Therefore, while a voltage closer tothe ground potential is output through the terminal 612, a power supplyvoltage of the negative polarity is output through the terminal 613.

Various circuits or circuit elements are formed on the element substrateand the power supply voltages to be supplied to the circuits of thecircuit elements vary depending on the kinds of the circuits of thecircuit elements or the purpose of use of the circuits of the circuitelements. In the rectifier circuit shown in FIG. 6, the level of thevoltage supplied to each terminal can be adjusted by controlling theamplitudes of input ac signals. Further, the levels of the power supplyvoltages supplied to the circuits of the circuit elements can be changedby changing the terminals for connection to the circuits of the circuitelements.

The rectifier circuit used in accordance with the present invention isnot limited to the half-wave rectifier circuit shown in FIG. 6. Anycircuit capable of generating a dc power supply voltage from an input acsignal may suffice as the rectifier circuit in accordance with thepresent invention.

FIGS. 18A and 18B are circuit diagrams showing rectifier circuitsdiffering in structure from that shown in FIG. 6. The rectifier circuitshown in FIG. 8A is a voltage-doubler full-wave rectifier circuit 901having two diodes 902 and 903, and capacitors 904 and 905. The positionsand the number of capacitors are not limited to those shown in FIG. 18A.

Both the cathode of the diode 902 and the anode of the diode 903 areconnected to one terminal of one input secondary coil. It is possible toobtain a dc voltage twice as high as that obtained by the half-waverectifier circuit shown in FIG. 6 by providing a plurality ofvoltage-doubler full-wave rectifier circuits 901 and by adding togetherthe outputs from the rectifier circuits 901.

The rectifier circuit shown in FIG. 8B is a bridge rectifier circuit 911having four diodes 912, 913, 914, and 915, which form a bridge circuit.The bridge rectifier circuit shown in FIG. 8B also has a capacitor 916.The positions and the number of capacitors are not limited to thoseshown in FIG. 18B.

The structure of the inspection-only circuit 119 shown in FIG. 2 will bedescribed in detail.

FIG. 9 shows the structure of the inspection-only circuit 119. Theinspection-only circuit 119 has means for performing signal processingon outputs from the circuits of the circuit elements, which are objectsto be inspected, to obtain signals (operation information signals)including information on the operating conditions of the inspectedcircuits or circuit elements. In this embodiment, an analog to digital(A/D) converter circuit 223 and a data format section 224 are used asthis processing means.

Analog outputs from the circuits of the circuit elements in the signalline drive circuit 111, the scanning line drive circuit 112, and thepixel portion 113 are converted into digital signals in the A/Dconverter circuit 223. The digital signals are input to the data formatsection 224. If the outputs from the circuits of the circuit elementsare not analog signals but digital signals, the digital signals areinput directly to the data format section 224.

In this embodiment, all the signals output from the circuits of thecircuit elements are converted into digital signals on which processingis performed in the data format section 224. However, the presentinvention is not limited to this arrangement. All the signals outputfrom the circuits of the circuit elements may be converted into analogsignals, which are processed in the data format section 224.

In the data format section 224, computational processing is performed onthe input digital signals corresponding to the circuits of the circuitelements to form an operation information signal, which is a signalincluding information on the operating conditions of the inspectedcircuits or circuit elements. More specifically, the operationinformation signals may be a serial signal converted from digitalsignals by temporarily storing the digital signals which are input inparallel with each other, and by sequentially reading out the storeddigital signals, or signals obtained in such a manner that the voltagesof digital signals input in parallel with each other are successivelyoutput in accordance with predetermined timing. The voltage of theoperation information signals output from the data format section 224may be changed in correspondence with the difference between a casewhere the outputs from the inspected circuits or circuit elements aredigital signals having the same voltage and a case where the outputs aredigital signals but the voltage of at least one of the digital signalsis different from that of the others. Any operation information signalmay suffice if it enables determination as to whether each inspectedcircuit or circuit element is defective or non-defective andascertainment of the location of a defective portion.

The operation information signal output from the data format section 224is amplified by a buffer 222 and is input to the modulation circuit 121.The arrangement may alternatively be such that the buffer 222 is notprovided and the output from the data format section 224 is inputdirectly to the modulation circuit 121.

On the other hand, the inspection ac signal is input to each inputprimary coil 208 from the ac power supply 202. When the ac signal isinput to the input primary coil 208, an ac voltage is generated aselectromotive force across the corresponding input secondary coil 207and this ac voltage is applied to the modulation circuit 121.

The modulation circuit 121 has means for modulating the amplitude of theac voltage input from the input secondary coil 207 with the operationinformation signal input from the data format section 224 or the buffer222. In FIG. 9, transistors 220 and 221 are provided as this modulationmeans. However, the present invention is not limited to thisarrangement. The modulation circuit 121 may be provided with anystructure if it can modulate the amplitude of the ac voltage input fromthe input secondary coil 207 with the operation information signal inputfrom the data format section 224 or the buffer 222.

In the modulation circuit 121 shown in FIG. 9, the output from thebuffer 222 is input to the gate electrodes of the transistors 220 and221. One of the source and drain regions of the transistor 220 isconnected to the first terminal of the input secondary coil 207, whilethe other of the source and drain regions is connected to the firstterminal of the output primary coil 210. One of the source and drainregions of the transistor 221 is connected to the first terminal of theoutput primary coil 210, while a constant voltage is applied to theother of the source and drain regions. This constant voltage may be theground potential.

In the above-described arrangement, the voltage of the alternatingcurrent output from the input secondary coil 207 is modulated with theoperation information signal and is input as a modulated signal to thefirst terminal of the output primary coil 210. In this embodiment, theac voltage output from the input secondary coil 207 is modulated in aswitching manner with the operation information signal to be input as amodulated signal to the first input terminal of the output primary coil210.

A constant voltage is similarly applied to the respective secondterminals of the input secondary coil 207 and the output primary coil210. This constant voltage may be the ground potential.

When the output primary coil 210 and the output secondary coil 211 areelectromagnetically coupled to each other, an ac voltage is generated aselectromotive force between the pair of terminals of the outputsecondary coil 211. This ac voltage is input to the inspection section203.

The inspection section 203 can ascertain whether each inspected circuitor circuit operates normally from the ac voltage input from the outputsecondary coil 211.

If the frequency of the ac voltage input to the inspection-only circuitis increased, the frequency of the modulated signal supplied from theinspection-only circuit to the terminal of each output primary coil isalso increased. The impedance of the coil is determined by variousfactors, e.g., coil design, including the number of turns and the sizeof the coil, and the frequency of the signal input to the coil.Therefore it is desirable that the frequency of the ac voltage beforemodulation, which is input to the inspection-only circuit be determinedby considering the other factors essential in determination of the coilimpedance value.

The operation information signal may have a dc component in some cases,depending on the operating condition of the inspected circuit or circuitelement. Even if the operation information signal has a dc component, itis possible to produce, between the terminals of the output secondarycoil, electromotive force including information on adefective/non-defective condition by supplying the ac modulated signalformed by modulation with the operation information signal to theterminal of the output primary coil.

This embodiment mode has been described with respect to an elementsubstrate having drive circuits, i.e., a signal line drive circuit and ascanning line drive circuit, as an example. However, element substratesinspected in accordance with the present invention are not limited tothis type of element substrate. Even an element substrate having only apixel portion can be inspected by using the inspection method of thepresent invention. Also, test circuits to be evaluated, which is calleda test element group (TEG), and which is a group of discrete componentsor a group of circuits composed of discrete components, can also beinspected by using the inspection method and inspection device of thepresent invention to inspect the operating condition.

While this embodiment mode has been described with respect to the methodof inspecting an element substrate of a liquid crystal display,semiconductor display devices other than liquid crystal displays canalso be inspected by using the inspection method described in thedescription of the mode of implementation. Also, any semiconductordevices utilizing the characteristics of a semiconductor formed on asubstrate, not limited to semiconductor display devices, can beinspected by using the inspection method of the present invention. Suchsemiconductor devices include a semiconductor device using asemiconductor thin film formed on a glass substrate, and a semiconductordevice Ruined on a monocrystalline silicon substrate.

However, it is necessary to suitably design the coils by selecting thenumber of coils, etc., according to the kind and the specifications ofthe semiconductor device. It is also necessary to suitably set thewaveform, frequency and amplitude of the inspection ac signal input toeach input primary coil formation portion according to the kind and thespecifications of the semiconductor device.

With the above-mentioned arrangements, the present invention enablesdetermination of a defective/non-defective condition without settingprobes directly on wirings. The possibility of minute dust beingproduced by setting probes is eliminated to prevent a reduction in yieldin subsequent processes. The inspection method of the present invention,unlike optical inspection methods, enables determination ofdefective/non-defective results of all the pattern forming steps by oneinspection step, thus simplifying the inspection step.

Embodiments of the present invention will be described below.

Embodiment 1

Embodiment 1 of the present invention will be described with respect toan example of inspection performed in such a manner that while no outputprimary coils and no output secondary coils are provided, weakelectromagnetic waves or electric fields generated when circuits of thecircuit elements are driven are monitored to detect a portion notoperating normally in a multiplicity of the circuits or circuitelements.

FIG. 10 shows the structures of an element substrate 455 and aninspection substrate 454 in this embodiment. The element substrate 455has an inspection-only circuit 419. The inspection-only circuit 419 hasmeans for performing signal processing on outputs from the circuits ofthe circuit elements, which are objects to be inspected, to form signals(operation information signals) including info nation on the operatingconditions of the inspected circuits or circuit elements. In thisembodiment, an A/D converter circuit 473 and a data format section 474are used as this processing means.

In this embodiment, the element substrate 455 has a signal line drivecircuit 411, a scanning line drive circuit 412, and a pixel portion 413.Analog outputs from the circuits of the circuit elements in the signalline drive circuit 411, the scanning line drive circuit 412, and thepixel portion 413 are converted into digital signals in the A/Dconverter circuit 473. The digital signals are input to the data formatsection 474. If the outputs from the circuits of the circuit elementsare not analog signals but digital signals, the digital signals areinput directly to the data format section 474.

In this embodiment, all the signals output from the circuits of thecircuit elements are converted into digital signals on which processingis performed in the data format section 474. However, the presentinvention is not limited to this arrangement. All the signals outputfrom the circuits of the circuit elements may be converted into analogsignals, which are processed in the data format section 474.

In the data format section 474, computational processing is performed onall the input digital signals corresponding to the circuits of thecircuit elements to form operation information signals, which includeinformation on the operating conditions of the inspected circuits orcircuit elements.

The operation information signals output from the data format section474 are amplified by a buffer 472 and are input to a modulation circuit421. The arrangement may alternatively be such that the buffer 472 isnot provided and the output from the data format section 474 is inputdirectly to the modulation circuit 421.

On the other hand, an inspection ac signal is input from an ac powersupply 452 to each of input primary coils 458 provided on the inspectionsubstrate 454. When the ac signal is input to the input primary coil458, an ac voltage is generated as electromotive force across thecorresponding one of input secondary coils 457 provided on the elementsubstrate 455 and this ac voltage is applied to the modulation circuit421.

The modulation circuit 421 has means for modulating the amplitude of theac voltage input from the input secondary coil 457 with the operationinformation signal input from the data format section 474 or the buffer472. In FIG. 10, transistors 470 and 471 are provided as this modulationmeans. However, the present invention is not limited to thisarrangement. The modulation circuit 421 may be provided with anystructure if it can modulate the amplitude of the ac voltage input fromthe input secondary coil 457 with the operation information signal inputfrom the data format section 474 or the buffer 472.

In the modulation circuit 421 shown in FIG. 10, the output from thebuffer 472 is input to the gate electrodes of the transistors 470 and471. One of the source and drain regions of the transistor 470 isconnected to the first terminal of the input secondary coil 457, whilethe other of the source and drain regions is connected to an output pad459 provided on the element substrate 455. One of the source and drainregions of the transistor 471 is connected to the output pad 459, whilea constant voltage is applied to the other of the source and drainregions. This constant voltage may be the ground potential.

A constant voltage is applied to the second terminal of the inputsecondary coil 457. This constant voltage may be the ground potential.

In the above-described arrangement, the ac voltage output from the inputsecondary coil 457 is modulated with the operation information signaland is input as a modulated signal to the output pad 459.

A weak electromagnetic wave or electric field is generated at the outputpad 458. In a measuring section 460 provided separately from theinspection substrate 454 and the element substrate 455, thiselectromagnetic wave or electric field is monitored to obtain as data tobe input to an inspection section 453. In the inspection section 453, itis possible to ascertain, from this data, whether the inspected circuitor circuit element is operating normally.

Any of various sorts of information on the electromagnetic wave orelectric field can be monitored and used. More specifically, it ispossible to collect the frequency, phase, intensity, time, etc., asinformation on the electromagnetic wave or electric field in variousdimensions. According to the present invention, any sort of informationon the electromagnetic wave or electric field may be used if it enablesdetection of a portion not operating normally in the multiplicity of thecircuits or circuit elements.

A well-known method may be used as a method of monitoring the weakelectromagnetic wave or electric field generated at each circuit orcircuit element. In the description of this embodiment, an example of amethod in which the electric field generated at each circuit or circuitelement is detected in the inspection step by using an electro-opticaleffect, more specifically a method for measurement using a Pockels cellwill be described.

The Pockels cell is one of electro-optical devices using the Pockelseffect which is one of the known electro-optical effects. Anelectro-optical device is an element using an electro-optical effectsuch that the refractive index of an element changes when an electricfield is applied to the element. The device can be used to modulate orshut off light or to generate or detect circularly polarized light byutilizing this characteristic, i.e., by applying an ac voltage or apulse voltage to a crystal

The Pockels cell has a first electrode, a second electrode, and aPockels crystal which is a ferroelectric crystal. The Pockels crystal isinterposed between the first and second electrodes. Each of the firstand second electrodes is made of a translucent electroconductivematerial.

A constant voltage is applied to the first electrode. The first andsecond electrodes are placed parallel to the element substrate so thatthe second electrode and the output pad 458 are superposed on oneanother. The second electrode may be placed adjacent to the elementsubstrate 455 or spaced a certain distance apart from the elementsubstrate 455. A cushioning material may be interposed between thesecond electrode and the element substrate 455.

The index of refraction of light at the portion of the Pockels cellsuperposed on the output pad 458 is changed by the electric fieldgenerated from the output pad 458. This refractive index is changedaccording to the intensity of the electric field generated from theoutput pad 458. Therefore, the intensity of the electric field generatedfrom the output pad 458 can be measured by monitoring the index ofrefraction of light at the Pockels cell.

More specifically, light traveling along a direction perpendicular tothe element substrate in the light passing through the Pockels cell isseparated by using an optical system component such as a polarizing beamsplitter, the intensity of the separated light is monitored and therefractive index of the Pockels cell is computed from the monitoredintensity of light. The voltage applied to the Pockels cell can beobtained from the refractive index. It is possible to detect a defectiveportion from the voltage applied to the Pockels cell.

Some computational processing may be performed on the results ofmonitoring performed a certain number of times to make determination ofa defective/non-defective condition.

The output from each inspected circuit is input to the inspection-onlycircuit and the intensity of the electromagnetic wave or electric fieldgenerated at the output pad is measured with an electro-optical device.In this method, there is no need to individually monitor each inspectedcircuit or circuit element by using a Pockels cell at the inspectedcircuit or circuit element, thus simplifying the inspection step andreducing the inspection time.

The Pockels crystal used in this embodiment may be typically a crystalof NH₄H₂PO₄, BaTiO₃, KH₂PO₄(KHP), KD₂PO₄(KDP), LiNbO₃, ZnO, or the like.The Pockels crystal used in this embodiment, however, is not limited tothe crystal of these materials. Any crystal suffices if it has a Pockelseffect.

The electro-optical device used to sense the electric field intensity inthis embodiment is not limited to the Pockels cell. Any electro-opticaldevice designed to utilize a phenomenon in which its opticalcharacteristic is changed by application of a voltage can be used in theinspection method or the inspection device of the present invention.Therefore, a liquid crystal may be used in the method or the device ofthe present invention.

In this embodiment, if the frequency of the ac voltage input to theinspection-only circuit is increased, the frequency of the modulatedsignal input from the inspection-only circuit to the output pad is alsoincreased.

Embodiment 2

Inspection drive signals and power supply voltages in a liquid crystaldisplay and an OLED display will be described in more detail as anexample.

The number of primary and secondary coils is changed according to theconstructions of the pixel portion and the drive circuits on the elementsubstrate. Therefore it is important to set the number of coilsaccording to the specifications of each element substrate.

FIG. 11 shows the structure of circuits on an element substrate of anordinary liquid crystal display. The element substrate shown in FIG. 11has a signal line drive circuit 700, a scanning line drive circuit 701,and a pixel portion 702.

A plurality of signal lines and a plurality of scanning lines are formedin the pixel portion 702. A region between signal lines and betweenscanning lines corresponds to a pixel forming segment. Only a pixelforming segment with one signal line 703 and one scanning line 704,which is representative of a plurality of pixels, is shown in FIG. 11.Each pixel forming segment has a pixel TFT 705 formed as a switchingelement and a pixel electrode 706 for driving a liquid crystal cell.

The gate electrode of the pixel TFT 705 is connected to the scanningline 704. One of the source and drain regions of the pixel TFT 705 isconnected to the signal line 703, while the other of the source anddrain regions is connected to the pixel electrode 706.

The signal line drive circuit 700 has a shift register 710, a levelshifter 711, and an analog switch 712. Power supply voltages (PowerSupply) are supplied to the shift register 710, the level shifter 711,and the analog switch 712. A signal line drive circuit clock signal(S-CLK) and a start pulse signal (S-SP) are supplied to the shiftregister 710. Video signals are supplied to the analog switch 712.

When the clock signal (S-CLK) and the start pulse signal (S-SP) areinput to the shift register 710, a sampling signal which determinestiming of sampling of video signals is generated and input to the levelshifter 711. The amplitude of the voltage of the sampling signal isincreased by the level shifter 711, and the sampling signal is theninput to the analog switch 712. In the analog switch 712, the inputvideo signals are sampled in synchronization with the input samplingsignal and the sampled video signals are input to the signal line 703.

On the other hand, the scanning line drive circuit has a shift register721 and a buffer 722. Power supply voltages (Power Supply) are suppliedto the shift register 721 and the buffer 722. A scanning line drivecircuit clock signal (G-CLK) and a start pulse signal (G-SP) aresupplied to the shift register 721.

When the clock signal (G-CLK) and the start pulse signal (G-SP) areinput to the shift register 721, a selection signal which determinestiming of selection of the scanning lines is generated and input to thebuffer 722. The selection signal input to the buffer 722 is buffered andamplified and is then input to the scanning line 704.

When the scanning line 704 is selected, the pixel TFT 705 whose gate isconnected to the selected scanning line 704 is turned on. The sampledvideo signal input to the signal line is supplied to the pixel electrode706 through the pixel TFT 705 in the on state.

When the signal line drive circuit 700, the scanning line drive signal701 and the pixel portion 702 operate as described above, the outputsfrom the circuits of the circuit elements (End Signals) are input to aninspection-only circuit 730. In the inspection-only circuit, operationinformation signals are formed from the outputs from the circuits of thecircuit elements and modulated signals are formed by modulation with theoperation information signals. The modulated signals are input to outputprimary coils. AC voltages thereby generated in output secondary coilsare input to an inspection section. In the inspection section, the inputvoltages are inspected to determine whether each circuit or circuitelement is operating normally. The arrangement may alternatively be suchthat when the signal line drive circuit 700, the scanning line drivecircuit 701 and the pixel portion 702 operate, electromagnetic waves orelectric fields generated at the circuits of the circuit elements aremonitored by using some means to determine whether each circuit orcircuit element is operating normally.

For example, in a case where the shift register 710 is formed by using aplurality of flip-flops, a voltage supplied to aid stored in the firstflip-flop is supplied to and stored in the second flip-flop, thensupplied to and stored in the third flip-flop, and so on insynchronization with S-CLK. The plurality of flip-flops operatesuccessively to forward the voltage in this manner. In the samplingsignal obtained by the flip-flops thus operating, a pulse appears attimes shifted one from another. If the flip-flop in one stage does notoperate normally, the flip-flops in the subsequent stages are unable tooperate normally. In this shift register, therefore, the sampling signalobtained as a result of the operation of the flip-flop in the finalstage can be used as an output (End Signal). The output obtained whenone of the flip-flops of the shift register has a defective portion anddoes not operate normally differs in voltage waveform from the outputobtained when all the flip-flops operate normally.

In the element substrate shown in FIG. 11, S-CLK, S-SP, G-CLK, G-SP, andvideo signals are input to the circuits as drive signals for inspection.However, drive signals used for inspection in accordance with thepresent invention are not limited to those described above. Any signalscan be used as drive signals for inspection as long as they relate todrive. For example, a signal for determining the timings at which thedirection of scanning with the scanning lines is changed and a signalfor changing the direction of input of the selection signal to thescanning lines may be input as well as the above-described signals.However, it is essential to input a signal which enables determinationof a defective/non-defective condition of each inspected circuit orcircuit element.

In a case where not all the circuits but part of the circuits formed onthe element substrate are inspected, it is not necessary to input allthe above-described drive signals if determination of adefective/non-defective condition of the inspected circuits can be made.For example, when only the shift register 710 in the signal line drivecircuit 700 is inspected, only inspection drive signals S-CLK and S-SPand the power supply voltage for inspection of the shift register 710may be formed in the waveform shaping circuit and the rectifier circuitand input to the shift register 710.

FIG. 12 shows the structure of circuits on an element substrate of anordinary OLED display. Drive circuits of an OLED display which displaysan image by using digital video signals will be described with referenceto FIG. 12 as an example. The element substrate shown in FIG. 12 has asignal line drive circuit 800, a scanning line drive circuit 801, and apixel portion 802.

A plurality of signal lines, a plurality of scanning lines and aplurality of power supply lines are formed in the pixel portion 802. Aregion surrounded by the signal lines, between the scanning lines, andthe power supply lines corresponds to a pixel forming segment. Only apixel forming segment with one signal line 807, one scanning line 809and one power supply line 808, which is representative of a plurality ofpixels, is shown in FIG. 12. Each pixel forming segment has a switchingTFT 803 formed as a switching element, a drive TFT 804, a storagecapacitor 805, and a pixel electrode 806 for driving an OLED.

The gate electrode of the switching TFT 803 is connected to the scanningline 809. One of the source and drain regions of the switching TFT 803is connected to the signal line 807, while the other of the source anddrain regions is connected to the gate electrode of the drive TFT 804.

One of the source and drain regions of the drive TFT 804 is connected tothe power supply line 808, while the other of the source and drainregions is connected to the pixel electrode 806. The gate electrode ofthe drive TFT 804 and the power supply line 808 form the storagecapacitor 805. It is not essentially necessary to form the holdingcapacitor 805.

The signal line drive circuit 800 has a shift register 810, a firstlatch 811, and a second latch 812. Power supply voltages (Power Supply)are supplied to the shift register 810, the first latch 811, and thesecond latch 812. A signal line drive circuit clock signal (S-CLK) and astart pulse signal (S-SP) are supplied to the shift register 810. Latchsignals for determining latch timing and video signals are supplied tothe first latch 811.

When the clock signal (S-CLK) and the start pulse signal (S-SP) areinput to the shift register 810, a sampling signal which determinestiming of sampling of video signals is generated and input to the firstlatch 811.

The sampling signal from the shift register 810 may be buffered andamplified by a buffer or the like before being input to the first latch811. Since many circuits or circuit elements are connected to the wiringto which the sampling signal is input, the load capacitance (parasiticcapacitance) of the wiring is large. This buffer is effective inpreventing “dulling” of the rising edge or falling edge of timing signalwhen the load capacitance is large.

The first latch 811 has a plurality of stages. In the first latch 811,the input video signals are sampled in synchronization with the inputsampling signal and the sampled video signals are successively stored inthe latches in the respective stages.

The time required to complete one cycle of writing video signals to thelatches in all the stages of the first latch 811 is called a lineperiod. In actuality, in some case, a period defined by adding ahorizontal retrace period to this line period is referred to as a lineperiod.

When one line period ends, latch signals are input to the second latch812. At this instant, the video signals written and held in the firstlatch 811 are fed to the second latch 812 all at once to be written toand stored in the latches in all the stages of the second latch 812.

After the video signals have been fed from the first latch 811 to thesecond latch 812, writing of the video signals to the first latch 811 issuccessively performed on the basis of the sampling signal from theshift register 810.

During the one line period in which the second cycle of writing isperformed, the video signals written and stored in the second latch 812are input to the source signal lines.

On the other hand, the scanning line drive circuit has a shift register821 and a buffer 822. Power supply voltages (Power Supply) are suppliedto the shift register 821 and the buffer 822. A scanning line drivecircuit clock signal (G-CLK) and a start pulse signal (G-SP) aresupplied to the shift register 821.

When the clock signal (G-CLK) and the start pulse signal (G-SP) areinput to the shift register 821, a selection signal which determinestiming of selection of the scanning lines is formed and input to thebuffer 822. The selection signal input to the buffer 822 is buffered andamplified and is then input to the scanning line 809.

When the scanning line 809 is selected, the switching TFT 803 whose gateelectrode is connected to the selected scanning line 809 is turned on.The video signal input to the signal line is supplied to the gateelectrode of the drive TFT 804 through the switching TFT 803 in the onstate.

Switching of the drive TFT 804 is controlled on the basis of ainformation bit of 1 or 0 supplied to the gate electrode. When the driveTFT 804 is on, the potential of the power supply line is applied to thepixel electrode. When the drive TFT 804 is off, the potential of thepower supply line is not applied to the pixel electrode.

When the signal line drive circuit 800, the scanning line drive signal801 and the pixel portion 802 operate as described above, the outputsfrom the circuits of the circuit elements (End Signals) are input to aninspection-only circuit 830. In the inspection-only circuit 830,operation information signals are generated from the outputs from thecircuits or the circuit elements and modulated signals are generated bymodulation with the operation information signals. The modulated signalsare input to output primary coils. AC voltages thereby generated inoutput secondary coils are input to an inspection section. In theinspection section, the input voltages are inspected to determinewhether each circuit or circuit element is operating normally. Thearrangement may alternatively be such that when the signal line drivecircuit 800, the scanning line drive circuit 801 and the pixel portion802 operate, electromagnetic waves or electric fields generated at thecircuits of the circuit elements are monitored by using some means todetermine whether each circuit or circuit element is operating normally.

In the element substrate shown in FIG. 12, S-CLK, S-SP, G-CLK, G-SP,latch signals, and video signals are input to the circuits as drivesignals for inspection. However, drive signals used for inspection inaccordance with the present invention are not limited to those describedabove. Any signals can be used as drive signals for inspection as longas they relate to drive. For example, a signal for determining thetimings at which the direction of scanning with the scanning lines ischanged and a signal for changing the direction of input of theselection signal to the scanning lines may be input as well as theabove-described signals. However, it is essential to input a signalwhich enables determination of a defective/non-defective condition ofeach inspected circuit or circuit element.

In a case where not all the circuits but part of the circuits formed onthe element substrate are inspected, it is not necessary to input allthe above-described drive signals, and only drive signals with which thepart of the circuits to be inspected are operated may be input. Forexample, when only the shift register 810 in the signal line drivecircuit 800 is inspected, only inspection drive signals S-CLK and S-SPand the power supply voltage for inspection of the shift register 810may be formed in the waveform shaping circuit and the rectifier circuitand input to the shift register 810.

If the power supply voltage is generated by adding together a pluralityof pulsating signals which differ in phase from each other, the numberof primary coils is also changed depending on the number of pulsatingsignals added.

Use of the inspection device and the inspection method of the presentinvention is not limited to inspection of the element substrate havingthe construction shown in FIGS. 11 and 12. The inspection device and theinspection method of the present invention can be used to inspectvarious kinds of semiconductor devices variously specified if operationinformation signals can be formed from outputs from the circuits or thecircuit elements when the semiconductor device is supplied with drivesignals and power supply voltages in a non-contact manner.

The present invention can be implemented by freely combining thisembodiment with Embodiment 1.

Embodiment 3

An embodiment of the present invention will be described which relatesto cutting of a large-size element substrate from which a plurality ofdisplay substrates are formed after inspection.

FIG. 13 is a top view of a large-size element substrate (also called anarray substrate) before the substrate is cut. A pixel portion 1001, ascanning line drive circuit 1002, and a signal line drive circuit 1003are provided on the element substrate. In the region indicated by 1004,there are formed circuits or circuit elements, such as a plurality ofinput secondary coils, a plurality of output primary coils, a waveformshaping circuit, a rectifier circuit, and an inspection-only circuit,which are used only in an inspection step, and which are not used afterthe completion of the inspection step.

The element substrate is cut along a line represented by a dotted linein FIG. 13, thus forming nine display substrates from one elementsubstrate. While this embodiment has been described with respect to acase where nine display substrates are formed from one elementsubstrate, the number of substrates obtained by dividing one largesubstrate in this embodiment is not limited to this number.

The element substrate is cut so that conductors in routing wiring andcoil wiring are cut and broken to effect physical and electricaldisconnection. On the element substrate shown in FIG. 13, the region1004 is provided on a substrate portion other than that used in adisplay after cutting.

An example of cutting of a large-size element substrate different fromthe cutting shown in FIG. 13 will be described with reference to FIG.14. A pixel portion 1101, a scanning line drive circuit 1102, and asignal line drive circuit 1103 are provided on the element substrate. Inthe region indicated by 1104, there are formed circuits or circuitelements, such as a plurality of input secondary coils, a plurality ofoutput primary coils, a waveform shaping circuit, a rectifier circuit,and an inspection-only circuit, which are used only in an inspectionstep, and which are not used after the completion of the inspectionstep.

The element substrate is cut along a line represented by a dotted linein FIG. 14, thus forming nine display substrates from one elementsubstrate. While this embodiment has been described with respect to acase where nine display substrates are formed from one elementsubstrate, the number of substrates obtained by dividing one largesubstrate in this embodiment is not limited to this number.

The element substrate is cut so that conductors in routing wiring andcoil wiring are cut and broken to effect physical and electricaldisconnection. On the element substrate shown in FIG. 14, the region1104 is provided on the substrate cutting line. The circuits or thecircuit elements in the region 1104 are cut and broken after inspection.Since the circuits or the circuit elements formed in the region 1104 areunnecessary after inspection, there is no problem with the operation ofthe completed semiconductor device.

Also, the waveform shaping circuit or the rectifier circuit may be lefton the substrate used in the semiconductor device or on the substratenot used in the semiconductor device after cutting, and may be brokenafter cutting.

The present invention can be implemented by freely combining thisembodiment with the arrangement of Embodiment 1 or 2.

Embodiment 4

A fourth embodiment of the present invention will be described withrespect to steps in an inspection step with reference to the flowchartof FIG. 15.

In the inspection step of the present invention shown in FIG. 15, aftera manufacturing process, inspection power supply voltages or drivesignals are input to the circuits or the circuit elements which areobjects to be inspected.

The circuits or the circuit elements to be inspected are made to operateby being supplied with the inspection power supply voltages or drivesignals, outputs from the circuits or the circuit elements are input tothe inspection-only circuit, and operation information signals aregenerated in the inspection-only circuit.

The amplitude of an ac signal input to the inspection-only circuit ismodulated with the operation information signals to form modulatedsignals, which are input to output primary coils. The output primarycoils and output secondary coils are electromagnetically coupled togenerate ac voltages across the output secondary coils. The ac voltagesare input to the inspection section.

In the inspection section, it is possible to make determination of adefective/non-defective condition and to locate a defective portion.More specifically, the ac signal amplitude to be input to the inspectionsection when one circuit element is operating normally and the amplitudeof the ac signal actually input to the inspection section when thecircuit element to be inspected is operated are compared with eachother.

Alternatively, the amplitudes of the ac signals input from the identicalcircuits or circuit elements to the inspection section may be comparedwith each other or the amplitude value obtained by actual measurementmay be compared with an amplitude value derived from a theoretical valuecomputed on the basis of a simulation.

If the comparison result shows that the amplitude of the voltage of oneof the ac signals input to the inspection section differs largely fromthe desired value, it is determined that the circuit or the circuitelement corresponding to the different amplitude is defective.

Therefore, it is also possible to simultaneously ascertain the operatingcondition of each circuit or circuit element and the location of adefective portion. A person who carries out the present invention mayset a suitable criterion on which determination is made as to whethereach circuit or circuit element is operating normally. A criterion maybe set such that when only one defective portion exists, it isdetermined that the inspected substrate is defective. Alternatively, acriterion may be set such that when a certain number of defectiveportions exist, it is determined that the inspected substrate isdefective.

If it is determined that the inspected substrate is non-defective, thecompletion of inspection is recognized and the manufacturing processafter the inspection step is started.

If it is determined that the inspected substrate is defective, the stepof removing (lotting out) the substrate from the process not to completeit as a product or the step of ascertaining the cause of the defect isselected. In a case where a plurality of products are manufactured fromone large substrate, substrates obtained by cutting the large substrateare separated into non-defectives and defectives, and the defectives arelotted out.

In a case where the cause of a defect is ascertained and it isdetermined that the substrate can be repaired, the inspection step inaccordance with the present invention may be again performed afterrepairing to repeat the above-described steps. If it is determined thatthe substrate cannot be repaired, the substrate is lotted out at thispoint.

The present invention can be implemented by freely combining thisembodiment with any of the structures of Embodiments 1 to 3.

Embodiment 5

A fifth embodiment of the present invention will be described withrespect to details of coils used in accordance with the presentinvention and connections between the terminals of the coils and wiring(coil wiring).

Referring to FIG. 16A, a coil 1601 is formed on an insulating surfaceand an interlayer insulating film 1603 is formed on the insulatingsurface so as to cover the coil 1601. A contact hole is formed in theinterlayer insulating film 1603 and a coil wiring 1602 is formed on theinterlayer insulating film 1603 so as to connect to the coil 1601 viathe contact hole.

FIG. 16B is a cross-sectional view taken along the dot-dash line C-C′ ofFIG. 16A.

Referring to FIG. 16C, a coil wiring 1612 is formed on an insulatingsurface and an interlayer insulating film 1613 is formed on theinsulating surface so as to cover the coil wiring 1612. A contact holeis formed in the interlayer insulating film 1613 and a coil 1611 isformed on the interlayer insulating film 1613 so as to connect to thecoil wiring 1612 via the contact hole.

FIG. 16D is a cross-sectional view taken along the dot-dash line D-D′ ofFIG. 16A.

The method of forming coils used in accordance with the presentinvention is not limited to those described above. A spiral groove isformed by pattern forming an insulating film and a conductive film isformed on the insulating film so as to fill the groove. Thereafter theconductive film is etched or polished by chemical mechanical polishing(CMP) until the insulating film is exposed. The material of theconductive film is thereby left only in the groove. The material of theconductive film left in the groove can also be used as a coil.

The present invention can be implemented by freely combining thisembodiment with any of the structures of Embodiments 1 to 4.

Embodiment 6

A sixth embodiment of the present invention will be described withrespect to the structure of an inspection device for performinginspection in accordance with the inspection method of the presentinvention.

FIG. 17 is a block diagram of an inspection device 1700 in accordancewith the present invention. The inspection device 1700 shown in FIG. 17has a signal source or an ac power supply 1702 input primary coils 1720,and output primary coils 1721, the input primary coils 1720 and theoutput primary coils 1721 being formed on an inspection substrate 1701.The inspection device 1700 also has substrate fixing means 1704 capableof overlapping the input primary coils 1720 and input secondary coils1722 provided on an element substrate 1703 with a certain spacingmaintained therebetween, and also capable of overlapping the outputsecondary coils 1721 and output primary coils 1723 provided on theelement substrate 1703 with a certain spacing maintained therebetween.The inspection device 1700 further has means (inspection section 1705)for making a determination of a defective/non-defective condition fromac voltages generated across the output secondary coils 1721 frommodulated signals produced on the element substrate 1703.

While the signal source or ac power supply 1702 in this embodiment isregarded as part of the inspection device 1700, it is not essentiallynecessary for the inspection device of the present invention to includethe signal source or ac power supply 1702

AC signals produced in the signal source or ac power supply 1702 areinput to an external input buffer 1706 provided on the inspectionsubstrate 1701. The input ac signals are amplified or buffered andamplified by the external input buffer 1706 and are thereafter input tothe input primary coils 1720 provided on the inspection substrate 1701.

The inspection substrate 1701 and the element substrate 1703 arepositioned by the substrate fixing means 1704 so that the input primarycoils 1720 and the input secondary coils 1722 are superposed on eachother while being spaced a certain distance apart from each other.

Power supply voltages or drive signals generated from ac voltagesgenerated across the input secondary coils 1722 are input to thecircuits or the circuit elements provided on the element substrate 1703.The circuit provided on the element substrate 1703 to form the powersupply voltages or drive signals is the same as that described above indetail in the description of this embodiment mode, and will not bedescribed below.

Outputs from the circuits or the circuit elements 1712 are input to aninspection-only circuit 1730 having a modulation circuit 1731. Theinspection-only circuit 1730 generates operation information signalsfrom the outputs of the circuits or the circuit elements 1712, andinputs the operation information signals to the modulation circuit 1731.

On the other hand, ac voltages generated across the input secondarycoils 1722 are input to the modulation circuit 1731. In the modulationcircuit 1731, the input ac voltages are modulated with the operationinformation signals to form modulated signals. The formed modulatedsignals are input to the output primary coils 1723.

The inspection substrate 1701 and the element substrate 1703 arepositioned by the substrate fixing means 1704 so that the output primarycoils 1723 and the output secondary coils 1721 are superposed on eachother while being spaced a certain distance apart from each other.

AC voltages are generated across the output primary coils 1723. The acvoltages are amplified or buffered and amplified by an external outputbuffer 1732 and are thereafter input to the inspection section 1705.

In the inspection section 1705, the input ac voltages are converted intonumeric values, which are obtained as data (measured values) to besupplied to an computational section 1709 provided in the inspectionsection 1705.

In the computational section 1709, a determination is made on the basisof the input measured values as to whether each circuit or circuitelement is non-defective or defective. For example, a comparisondescribed below is made to enable this determination. The ac signalsinput to the inspection section when the circuit elements are operatingnormally are stored in a memory or the like, and the amplitude of eachof the ac signals actually input to the inspection section when thecircuit elements to be inspected are operated is compared with thecorresponding ac signal stored in the memory. Alternatively, theamplitudes of the ac signals input from the identical circuits orcircuit elements to the inspection section may be compared with eachother or the amplitude values obtained by actual measurement may becompared with amplitude values derived from theoretical values computedon the basis of a simulation.

The present invention is not limited to these examples of the comparisonmethod. Any method may be used if it enables detection of any one of thecircuit elements from which a significantly different ac signalamplitude is input to the inspection section compared with the ac signalamplitude input to the inspection section when the normal circuitelement is operated.

If the comparison result shows that the amplitude of one of the acsignals input to the inspection section is significantly different, itis determined that the corresponding circuit or circuit element isdefective. In actuality, in many cases, the amplitude of each ac signalinput to the inspection section varies in a certain cycle even if thecorresponding circuit is normal. In such a situation, the average valueof the amplitude in each cycle may be computed and compared with that ofthe normal components. Any method may be used for this comparison.

If electric fields or electromagnetic waves generated at the circuits orthe circuit elements are monitored for determination of adefective/non-defective condition, there is no need to provide theoutput primary coils 1723, the output secondary coils 1721, and theexternal output buffer 1732. In this case, output pads are provided onthe element substrate 1703 and modulated signals output from themodulation circuit 1723 are supplied to the output pads.

Also, a measuring section is provided in the inspection device, andelectric fields or electromagnetic waves generated at the output padsare monitored in the measuring section and obtained as data to besupplied to the computational section 1709 provided in the inspectionsection 1705. In the computational section 1709, a determination is madeon the basis of the input data as to the operating condition of eachcircuit or circuit element and the location of a defective portion.

The present invention can be implemented by freely combining thisembodiment with any of the structures of Embodiments 1 to 5.

The above-described structures of the present invention enabledetermination of a defective/non-defective condition of each inspectedcircuit or circuit element without setting probes directly on wirings orterminals. The possibility of minute dust being produced by settingprobes is eliminated to prevent a reduction in yield in subsequentprocesses. The inspection method of the present invention, unlikeoptical inspection methods, enables determination ofdefective/non-defective results of all the pattern forming steps by oneinspection step, thus simplifying the inspection step.

What is claimed is:
 1. A measuring method of a circuit or a circuitelement, comprising: operating the circuit or the circuit element byapplying a voltage to the circuit or the circuit element in anon-contact manner, and reading a voltage output from the circuit or thecircuit element in a non-contact manner.